1. Field of the Invention
The present invention relates to a process for - selectively preparing racemic or optically active cis-azole derivatives which are active ingredients of agricultural and horticultural compositions, and to intermediates for preparing the azole derivatives, a process for preparation thereof, and fungicidal compositions.
2. Description of the Related Art
Azole derivatives represented by the following general formula (I) have heretofore been known to have excellent agricultural and horticultural fungicidal effects and plant growth controlling effects, and a process for preparation thereof has been known too. ##STR3## wherein R.sup.1 and R.sup.2 mean a hydrogen atom or an alkyl group, independently, R denotes a halogen atom, a nitro group, independently, R denotes a halogen atom, a nitro group, a cyano group, an alkyl group, a haloalkyl group or a phenyl group, A denotes a nitrogen atom or a methine group, and n stands for 0 or an integer of 1-5.
Namely, EP-A-329397 discloses a process for preparation of a racemic mixture of cis-azole derivatives and trans-azole derivatives represented by the above general formula (I), and EP-A-267778 discloses a process for preparation of cis- or trans-azole derivatives represented by the general formula (I') ##STR4## wherein R.sup.1' and R.sup.2' denote each a C.sub.1 -C.sub.5 alkyl group or a hydrogen atom, but R.sup.1' and R.sup.2' are not hydrogen atom at the same time, X' denotes a halogen atom, a C.sub.1 -C.sub.5 alkyl group or a phenyl group, n' stands for 0 or an integer of 1 or 2, and A' denotes a nitrogen atom or a methine group, which comprises using cis- or trans-oxaspiroheptane derivatives represented by the general formula (II') ##STR5## wherein R.sup.1' and R.sup.2', X' and n have the same meanings as defined above.
It has been known that the azole derivatives represented by the general formula (I) has a higher activity in the cis form than in the trans form.
It is therefore desired to provide a process by which cis-form azole derivatives represented by the general formula (I) having a higher fungicidal activity are selectively prepared. In the process described in EP-A-329397, however, since a mixture of cis form and tans form is prepared, the yield of the cis form is reduced under the influence of the by-produced trans form and it is necessary to separate the cis-azole derivatives from the mixture of the cis form and trans form. Further, in the process described in Japanese Patent Application Laid-Open No. 93574/1989, a process for separating the cis form is required in a stage of preparing oxaspiroheptane derivatives represented by the general formula (II') in order to obtain the cis azole derivatives.
As be described above, the prior processes require a separation step for obtaining purified cis form. In the separation step, large amounts of column packings or solvents are used and a loss is caused when separation is carried out. Accordingly, it is not advantageous to combine the separation step in the industrial process for preparation of the cis form.
The present invention has been achieved in the light of the above described circumstances in the prior arts.